Cake clogging

This analysis assumes a uniform cake. Nonuniform cakes can be caused by cake clogging and cake compression. Cake dc ging can occur... 

Kwon, J.H. Effects of Compressibility and Cake Clogging on Sludge Dewatering Characteristics. Ph.D. Diss., Seoul National University, Korea, 1995. 

In Figure 22.24, resistance plots for p/ q versus are shown for a series of runs involving Kentucky No. 9 liquefied coal filter in the U.S. Filter Co. vertical leaf filter. They follow the general trends of filtrations subject to both medium and cake clogging as illustrated in Figure 22.23. 

Equipment Operation Spray nozzles suffer from caking on the outside and clogging on the inside. When the nozzle is below the bed surface, fast capture of the liquid drops by bed particles, as well as scouring of the nozzle by particles, prevents caking. Blockages inside the nozzle are also common, particularly for slurries. The nozzle design shoiild be as simple as possible and provision for in situ cleaning or easy removal is essential. 

Nonwoven filter media are mostly used for filter medium filtration with pore clogging. Because of the relatively low cost of this medium, it is often replaced after pore clogging. In some cases, nonwoven media are used for cake filtration. In this case, cake removal is so difficult that it must be removed altogether from the filter medium. Nonwoven filter media can be prepared so that pore sizes decrease in the direction from the surface of the filter media contacting suspension to the surface contacting the supporting device. This decreases the hydraulic resistance of... 

The most favorable filtration operation with cake formation is process whereby no clogging of the filter medium occurs. Such a process is observed at sufficiently high concentrations of solid particles in suspension. From a practical standpoint this concentration may conditionally be assumed to be in excess of 1% by volume. Filtration is frequently accompanied by hindered or free gravitational settling of solid particles. The relative directions of action between gravity force and filtrate... 

O When the cake tends to clog the cloth its continuous removal after cake discharge enables dislodging of particles by thorough washing of the cloth on both sides with high impact nozzles. 

The solid-liquid separation of shinies containing particles below 10 pm is difficult by conventional filtration techniques. A conventional approach would be to use a slurry thickener in which the formation of a filter cake is restricted and the product is discharged continuously as concentrated slurry. Such filters use filter cloths as the filtration medium and are limited to concentrating particles above 5 xm in size. Dead end membrane microfiltration, in which the particle-containing fluid is pumped directly through a polymeric membrane, is used for the industrial clarification and sterilisation of liquids. Such process allows the removal of particles down to 0.1 xm or less, but is only suitable for feeds containing very low concentrations of particles as otherwise the membrane becomes too rapidly clogged.2,4,8... 

Suspended particles may clog the pores, forming a filter-cake with reduced permeability. 

Commercially, separation is mostly performed by vacuum filtration on belt or drum filters or by pressure in membrane filters (Illingworth, 2002). Evenly-sized well-developed spherical crystals, such as those obtained in a well-executed Tirtiaux process, can be easily recovered using vacuum filters. For optimal filtration, the air on top of the filter may be cooled or heated to the filtration temperature to avoid melting or crystallization on the filter and clogging of the filter cake. This results in increasing entrainment and reducing filter speed. A considerable amount of oil is entrained in the filter cake, which can be as much as 60-70% for milk fat. 

Peeler centrifuges are also batch-continuous machines where the cake is removed by a plough. Different solids content feedstocks can therefore be handled in this type of unit, provided that they do not clog up the filter medium. A high degree of automation can be achieved with this type of unit. 

CINCLEAR T is much more stable than hydro and does not cake and form lumps which can clog lines from makeup tank to dye machine. 

The industry standard method for beer hltration is using diatomaceous earth (DE), a sand-like powder with a very high internal surface area and a hne porous strucmre, as a hlter aid in depth- and cake-type hltration. Conventional beer clarihcation employs hlter presses or pressure vessel hlters that are pre-coated with porous diatomaceous earth particles as hlter aids. In order to minimize clogging of the hltration media and maintain a porous cake, and thus extend the duration of the hltration mns, hlter aid is conhnuously metered into the unhltered beer as body feed [42]. 

MFI measurements are based on the formation of a cake or gel when water containing colloids are filtered through a membrane filter. Recently the use of the MFI parameter has been studied in relation to slow sand filtration performance 5 and in relation to clogging of injection wells [6 ]. 

Once all the solution has been filtered, immediately remove the filter paper to a large watch glass. Pour the filtrate back into the beaker, place a new piece of filter paper on the funnel, and filter this solution through again as above. Repeat a third time with the third piece of filter paper. This third filter cake may be thick and milky. Calcium oxalate precipitate causes this color and causes the filter to clog. If this occurs, the third filter cake should be discarded. 

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